I don’t think it’s silly to buy a new graphics card for 1 game, if that’s the 1 game you’ve primarily played for the past year. Right now, people are starting to get rid of their 30XX cards to buy 4090s, so it’s not a bad time to upgrade. There are 3090s on ebay for $500-600.
I think a main reason VR suffers in MSFS is because it’s such a large open-world.